In view of global concern regarding the environmental consequences attending the release of chlorofluorocarbon refrigerants into the atmosphere, there is now world-wide agreement regarding regulation of the production and use of chlorofluorocarbons. As a result of this regulation the cost of chlorofluorocarbon refrigerants is expected to rise dramatically.
Accordingly, there has arisen an interest in recovering refrigerant fluids. Commonly assigned U.S. Pat. No. 4,766,733, the disclosure of which is incorporated herein by reference, describes an apparatus for recovering chlorofluorocarbon refrigerants.
The need to provide field service for refrigeration equipment requires that refrigerant recovery devices be readily portable, e.g. so that a service person may transport the recovery device from his vehicle to a rooftop air conditioning unit without undue time and effort.
Known portable CFC recovery units include a conventional refrigerant compressor for transferring refrigerant from an apparatus, e.g. a refrigeration unit, to a receiver, e.g. a pressure vessel. The use of a conventional refrigerant compressor in a portable CFC recovery unit has several drawbacks.
The ease of portability of a particular portable CFC recovery unit depends, to a large extent, upon the weight of the unit. A conventional 1/2 HP refrigerant compressor weights about 40 pounds and accounts for a significant portion of the overall weight, i.e. between about 70 lb and about 100 lb, of a typical recovery unit.
The difficulties associated with using conventional refrigerant compressors in a portable CFC recovery unit are acknowleged by the industry, see e.g. "The Perfect HCFC Recovery Machine" by J. Wheeler, Contracting Business. October 1990, page 7, and "`Don't Wait To Buy Recyclers` MFRS Tell HVAC Contractors" by Peter Powell, The Air Conditioning, Heating and Refrigeration News, Oct. 7, 1991.
Furthermore, conventional refrigerant compressors are designed to operate on a closed loop wherein lubricant is carried in the refrigerant and is continuously cycled through the system. In an open loop refrigerant recovery system lubricant is not returned to the compressor potentially resulting in insufficient lubrication and premature wear of the compressor. This problem is aggravated by the need to pull a vacuum on the unit from which the refrigerant is being recovered. Furthermore, the lubricant in the refrigerant being recovered may include contaminants, e.g. hydrochloric acid and/or hydrofluoric acid, which may damage the compressor.